Reconstructing Environmental Interventions for People with Dementia — Preserving Core Active Ingredients While Reducing Cognitive and Implementation Burden

1. Introduction

1.1. Redefining the "Environment" in Dementia Care

The environment is not a curative factor in dementia. However, it exerts a powerful influence as a condition that can sharply exacerbate the course of the disease.

Inappropriate lighting, complex pathways, sudden stimuli, and unfamiliar changes in layout have repeatedly been reported to disrupt temporal orientation, spatial cognition, and safety judgment in people with dementia, leading to delirium, nighttime agitation, and falls (Fleming & Purandare, 2010; Oh & Fong, 2017). Figure 1 conceptually illustrates the cascade of acute deterioration triggered by these environmental factors.

What is particularly important is that the effects of these environmental factors are not the result of chronic neurodegeneration, but can worsen or improve within relatively short periods and are often reversible. Therefore, the environment should not be regarded as “ancillary care,” but rather as the most upstream lever for controlling progression-accelerating factors (WHO, 2017).

1.2. Limitations of Conventional Environmental Design Approaches

Conventional environmental design theories often aspire to ideal architectural or facility layouts and tend to rely on the following implicit assumptions:

• Major renovations or dedicated equipment are feasible.
• Caregivers are consistently able to optimize environmental conditions.
• The person with dementia can understand and adapt to changes in the environment.

However, in home-based and general care settings, these assumptions are rarely met. As a result, interventions that are theoretically sound often fail to be implemented in practice, becoming “correct but unworkable.”

This paper aims to reconstruct the concept of the environment from a design-centered approach to one focused on implementation.

2. Constraints on Environmental Interventions in Dementia Care

2.1. Cognitive Constraints: Impaired Processing of Temporal and Spatial Cues

In dementia, impairments in temporal orientation, visuospatial perception, and attention allocation occur from early stages.

Inconsistent lighting or disorganized spatial layouts can easily lead to misperceptions of time or spatial confusion.

2.2. Emotional and Behavioral Constraints: Overstimulation and Reactive BPSD

Unpredictable stimuli and noise often trigger behavioral and psychological symptoms of dementia (BPSD) through anxiety and fear.These symptoms should not be interpreted as intentional behaviors, but rather as reactive responses to the surrounding environment (Cohen-Mansfield, 2001).

2.3. Implementation Constraints: Person-Dependent Environmental Management

When environmental adjustments rely on caregiver effort or vigilance, sustainability is compromised.

The environment must function as a stable structure—not as a system dependent on human effort.

3. Differentiating Core Active Ingredients from Excessive Implementation Burdens

3.1. Core Active Ingredients in Environmental Interventions

The main challenge in implementing environmental interventions for dementia has not been a lack of effectiveness, but rather the conflation of effective elements with components that impose excessive cognitive or operational burdens.

In this section, we integrate existing studies and guidelines to decompose environmental interventions into "core active ingredients" and "components that should be eliminated due to their implementation burden" (see Figure 2).

The literature review identifies the following three elements as core active ingredients:

• Lighting that clarifies temporal cues for day and night

Providing sufficient brightness during the day and avoiding excessive lighting at night supports circadian rhythm stabilization and helps reduce nighttime agitation and delirium

(Rea & Figueiro, 2018; Van Hoof et al., 2009).

• Simplification of nighttime pathways and assurance of visibility

Fixing the walking route, using floor-level lighting, and removing obstacles can reduce the risk of falls

(Allan et al., 2009; NICE, 2013).

• Optimization of sensory stimulation

Reducing noise and sudden stimuli decreases the frequency of BPSD and delirium

(Livingston et al., 2014).

These three elements are all applicable without increasing environmental complexity, and as shown in Figure 2, they can be clearly distinguished from design features that impose excessive implementation burdens.

3.2. Implementation Burdens to Be Eliminated

• Frequent rearrangement of furniture or layout
• Excessive signage and information displays
• Requiring the person with dementia to understand and adapt to environmental changes
• Management dependent on caregiver attention and vigilance

4. Dementia-Adapted Minimal Environmental Intervention Model

4.1. Minimal Component ①: Bright Days, Dark Nights

To implement the core active ingredients sustainably in home and care settings, we propose a dementia-adapted minimal environmental intervention model (see Figure 3).

Key lighting principles include:

• Daytime: Maximize natural light and maintain sufficient indoor brightness.
• Nighttime: Use minimal lighting only to ensure footpath visibility.

4.2. Minimal Component ②: Fixed Nighttime Pathways

• Establish a consistent route from bed to toilet.
• Avoid rearranging furniture.

4.3. Minimal Component ③: Reduced Sensory Load

• Avoid keeping the television on continuously or at high volume.
• Minimize nighttime verbal interactions and sudden physical contact.

As shown in Figure 3, this model is characterized by transferring the responsibility for safety and predictability from the person to the environment itself, thereby maximizing emotional security and environmental predictability without relying on the individual's cognitive effort or adaptive capacity.

5. Implementation Protocol (Summary)

• Frequency: Continuous (applied at all times)
• Responsible party: The environment itself (do not place responsibility on the person with dementia)
• Inspection: Simple weekly checks

6. Implications for Research, Practice, and Policy

Figure 1 through 3 presented in this paper systematize environmental interventions for dementia in three dimensions:

• Positioning the environment as a progression-accelerating factor (Figure 1)
• Decomposing environmental interventions into active ingredients and implementation burdens (Figure 2)
• Proposing a minimal, implementable intervention model (Figure 3)

The value of environmental interventions should be assessed not by cognitive function scores, but by cost-related outcomes such as delirium, falls, hospitalizations, and institutionalization.

The novelty of this paper lies in redefining the environment not as a treatment, but as a means of controlling progression-accelerating conditions.

7. Conclusion

Environmental interventions for people with dementia represent one of the most cost-effective, immediate, and reproducible foundational strategies available.

By preserving the core active ingredients while eliminating excessive burdens, the environment can function as an implementation-science–based intervention that builds a “brain-friendly world.”

This concept is embodied in the minimal environmental intervention model presented in Figure 3.

Appendix

Environmental Adjustment Support Manual for People with Dementia

(Implementation Guide for Care and Home Settings)